package com.zch.zhongchou.util;

import java.security.MessageDigest;
/**
 * md5加密
 * @author Administrator
 *
 */
public class CheckSumBuilder {
   // 计算并获取CheckSum
   public static String getCheckSum(String appSecret, String nonce, String curTime) {
       return encode("sha1", appSecret + nonce + curTime);
   }
   
   // 计算并获取md5值
   public static String getMD5(String requestBody) {
       return encode("md5", requestBody);
   }
 
   private static String encode(String algorithm, String value) {
       if (value == null) {
           return null;
       }
       try {
           MessageDigest messageDigest
                   = MessageDigest.getInstance(algorithm);
           messageDigest.update(value.getBytes());
           return getFormattedText(messageDigest.digest());
       } catch (Exception e) {
           throw new RuntimeException(e);
       }
   }
   private static String getFormattedText(byte[] bytes) {
       int len = bytes.length;
       StringBuilder buf = new StringBuilder(len * 2);
       for (int j = 0; j < len; j++) {
           buf.append(HEX_DIGITS[(bytes[j] >> 4) & 0x0f]);
           buf.append(HEX_DIGITS[bytes[j] & 0x0f]);
       }
       return buf.toString();
   }
   private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5',
           '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
}
